The development of the Autonomic Nervous Control of Cardiorespiratory Systems will be studied at the Biochemical level. Measurements will be made of levels of catecholamines, and enzymes of catecholamine metabolism in heart and laryngeal muscles in new born and adult animals. In addition, serotonin and tryptophan hydroxylase will be measured in brain tissues. For the most part, enzymes will be detected by highly sensitive radioassays. Catecholamines will be determined by absorbing them to alumina, eluting them from alumina with dilute acetic acid and converting them to highly fluorescent products by oxidation. Serotonin will be isolated by extraction with butanol and quantitated by its fluorescence in acid solution. The resulting data will be correlated with ongoing studies of functional maturity of the autonomic nervous system in the same animal model. Enzymes of catecholamine and serotonin metabolism will also be analyzed in autopsied human tissues. Attempts will be made to evaluate the functional maturity of the autonomic nervous control of the cardiorespiratory system in infants from these data. In addition, tissues from infants having died of Sudden Infant Death Syndrome (SIDS) will be analyzed to test the hypothesis that these infants die of an Autonomic Disease which may be reflected at the biochemical level.